Plastic Fant­ast­ic: Green, Strong and Edible

Bil­lions of tons of plastic waste clut­ter our world. Most of it has accu­mu­lated on the ground and in the oceans or dis­in­teg­rated into tiny particles known as micro­plastics that pol­lute the air and the water, pen­et­rat­ing veget­a­tion and the blood­streams of humans and oth­er anim­als. The scope of the danger posed by plastics grows with each passing year, since they are made from massive molecules, known as poly­mers, that do not read­ily bio­de­grade. Cur­rently, bio­de­grad­able plastics make up less than one-fifth of the total amount of plastic pro­duced, and the pro­cesses needed to break them down are rel­at­ively cumbersome.

In a study pub­lished in ACS Nano, Dr. Angel­ica Niazov-Elkan, Dr. Haim Weiss­man and Prof. Bor­is Rybtch­in­ski of the Molecu­lar Chem­istry and Mater­i­als Sci­ence Depart­ment at the Weiz­mann Insti­tute of Sci­ence have cre­ated a new com­pos­ite plastic that degrades eas­ily using bac­teria. This new mater­i­al, pro­duced by com­bin­ing a bio­de­grad­able poly­mer with crys­tals from a bio­lo­gic­al sub­stance, has three major bene­fits: It is cheap, easy to pre­pare and very strong. Also par­ti­cip­at­ing in the study were the late Dr. Eyal Shi­moni, Dr. Xiao­Meng Sui, Dr. Yishay Feld­man and Prof. H. Daniel Wagner.

Cur­rently, many indus­tries are enthu­si­ast­ic­ally adopt­ing com­pos­ite plastics, which are made by com­bin­ing two or more pure mater­i­als and pos­sess the vari­ous bene­fi­cial prop­er­ties such as light­ness and strength. These plastics now serve to man­u­fac­ture key parts of a wide vari­ety of indus­tri­al products, from air­planes and cars to bicycles.

Seek­ing to cre­ate a com­pos­ite plastic that would meet the needs of industry while also being envir­on­ment­ally friendly, the Weiz­mann research­ers decided to focus on com­mon­place, inex­pens­ive source mater­i­als whose prop­er­ties could be improved. They found that molecules of tyr­osine – a pre­val­ent amino acid that forms excep­tion­ally strong nano­crys­tals – could be used as an effect­ive com­pon­ent in a bio­de­grad­able com­pos­ite plastic. After examin­ing how tyr­osine com­bines with sev­er­al types of poly­mers, they chose hydroxyethyl cel­lu­lose, a deriv­at­ive of cel­lu­lose, which is employed extens­ively in the man­u­fac­ture of medi­cines and cosmetics.

On its own, hydroxyethyl cel­lu­lose is a weak mater­i­al that dis­in­teg­rates read­ily. To com­bine it with tyr­osine, the two mater­i­als were mixed togeth­er in boil­ing water. When they cooled and dried, an excep­tion­ally strong com­pos­ite plastic was formed, made of fiber-like tyr­osine nano­crys­tals that grew into the hydroxyethyl cel­lu­lose and integ­rated with it. In one exper­i­ment that revealed the new plastic’s strength, a 0.04-millimeter-thick strip of the mater­i­al with­stood a load of 6 kilo­grams. Moreover, the team dis­covered that the new mater­i­al had sev­er­al oth­er unique char­ac­ter­ist­ics, mak­ing it even more use­ful for industry. Usu­ally, when a mater­i­al is strengthened, it loses plas­ti­city. This new com­pos­ite plastic, how­ever, in addi­tion to being very strong, is also more ductile (mal­le­able) than its core com­pon­ent, hydroxyethyl cel­lu­lose. In oth­er words, com­bin­ing the two mater­i­als cre­ated a syn­ergy that mani­fests itself in the emer­gence of extraordin­ary prop­er­ties and, con­sequently, has massive indus­tri­al potential.

Since both cel­lu­lose and tyr­osine – the crys­tals of which can be found in vari­ous types of hard cheese – are edible, the bio­de­grad­able com­pos­ite plastic can actu­ally be eaten. Is it also tasty? We will have to wait to find out: Since the pro­duc­tion pro­cess in the lab is not hygien­ic enough for food­stuffs, the research­ers are yet to have a nibble.

Weiz­mann Insti­tute research­ers have cre­ated a bio­de­grad­able com­pos­ite mater­i­al that might help battle the glob­al plastic-waste crisis
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Bor­is Rybtch­in­skiMolecu­lar Chem­istry and Mater­i­als Sci­en­ce­Pol­lu­tion­Cli­mate changeGreen Chem­istry
Bil­lions of tons of plastic waste clut­ter our world. Most of it has accu­mu­lated on the ground and in the oceans or dis­in­teg­rated into tiny particles known as micro­plastics that pol­lute the air and the water, pen­et­rat­ing veget­a­tion and the blood­streams of humans and oth­er anim­als. The scope of the danger posed by plastics grows with each passing year, since they are made from massive molecules, known as poly­mers, that do not read­ily bio­de­grade. Cur­rently, bio­de­grad­able plastics make up less than one-fifth of the total amount of plastic pro­duced, and the pro­cesses needed to break them down are rel­at­ively cumbersome.

(l‑r) Prof. Bor­is Rybtch­in­ski, Dr. Haim Weiss­man and Dr. Angel­ica Niazov-Elkan

In a study pub­lished in ACS Nano, Dr. Angel­ica Niazov-Elkan, Dr. Haim Weiss­man and Prof. Bor­is Rybtch­in­ski of the Molecu­lar Chem­istry and Mater­i­als Sci­ence Depart­ment at the Weiz­mann Insti­tute of Sci­ence have cre­ated a new com­pos­ite plastic that degrades eas­ily using bac­teria. This new mater­i­al, pro­duced by com­bin­ing a bio­de­grad­able poly­mer with crys­tals from a bio­lo­gic­al sub­stance, has three major bene­fits: It is cheap, easy to pre­pare and very strong. Also par­ti­cip­at­ing in the study were the late Dr. Eyal Shi­moni, Dr. Xiao­Meng Sui, Dr. Yishay Feld­man and Prof. H. Daniel Wagner.

Cur­rently, many indus­tries are enthu­si­ast­ic­ally adopt­ing com­pos­ite plastics, which are made by com­bin­ing two or more pure mater­i­als and pos­sess the vari­ous bene­fi­cial prop­er­ties such as light­ness and strength. These plastics now serve to man­u­fac­ture key parts of a wide vari­ety of indus­tri­al products, from air­planes and cars to bicycles.

Top: A sheet of the new bio­de­grad­able com­pos­ite plastic cre­ated in a Weiz­mann Insti­tute lab. Bot­tom: Elec­tron micro­scope images show­ing the mater­i­al from above (left), in cross-sec­tion (cen­ter) and in a close-up of the cross-sec­tion (right)

Seek­ing to cre­ate a com­pos­ite plastic that would meet the needs of industry while also being envir­on­ment­ally friendly, the Weiz­mann research­ers decided to focus on com­mon­place, inex­pens­ive source mater­i­als whose prop­er­ties could be improved. They found that molecules of tyr­osine – a pre­val­ent amino acid that forms excep­tion­ally strong nano­crys­tals – could be used as an effect­ive com­pon­ent in a bio­de­grad­able com­pos­ite plastic. After examin­ing how tyr­osine com­bines with sev­er­al types of poly­mers, they chose hydroxyethyl cel­lu­lose, a deriv­at­ive of cel­lu­lose, which is employed extens­ively in the man­u­fac­ture of medi­cines and cosmetics.

On its own, hydroxyethyl cel­lu­lose is a weak mater­i­al that dis­in­teg­rates read­ily. To com­bine it with tyr­osine, the two mater­i­als were mixed togeth­er in boil­ing water. When they cooled and dried, an excep­tion­ally strong com­pos­ite plastic was formed, made of fiber-like tyr­osine nano­crys­tals that grew into the hydroxyethyl cel­lu­lose and integ­rated with it. In one exper­i­ment that revealed the new plastic’s strength, a 0.04-millimeter-thick strip of the mater­i­al with­stood a load of 6 kilo­grams. Moreover, the team dis­covered that the new mater­i­al had sev­er­al oth­er unique char­ac­ter­ist­ics, mak­ing it even more use­ful for industry. Usu­ally, when a mater­i­al is strengthened, it loses plas­ti­city. This new com­pos­ite plastic, how­ever, in addi­tion to being very strong, is also more ductile (mal­le­able) than its core com­pon­ent, hydroxyethyl cel­lu­lose. In oth­er words, com­bin­ing the two mater­i­als cre­ated a syn­ergy that mani­fests itself in the emer­gence of extraordin­ary prop­er­ties and, con­sequently, has massive indus­tri­al potential.

Since both cel­lu­lose and tyr­osine – the crys­tals of which can be found in vari­ous types of hard cheese – are edible, the bio­de­grad­able com­pos­ite plastic can actu­ally be eaten. Is it also tasty? We will have to wait to find out: Since the pro­duc­tion pro­cess in the lab is not hygien­ic enough for food­stuffs, the research­ers are yet to have a nibble.

Rybtch­in­ski sums up: ​“The fol­low-up study that we have already star­ted could advance the com­mer­cial poten­tial of this new mater­i­al, since we have replaced the boil­ing in water with melt­ing, as is more com­mon in industry. This means that we heat up the bio­de­grad­able poly­mers until they become liquid and then mix in the tyr­osine or oth­er suit­able mater­i­als. If we man­age to over­come the sci­entif­ic and tech­nic­al chal­lenges involved in this pro­cess, we will be able to explore the pos­sib­il­ity of pro­du­cing this new com­pos­ite plastic on an indus­tri­al scale.”
 

The ori­gin­al pub­lic­a­tion can be found here.